Hi dean,
Put a straight edge on the head and have a good look. It hay have rounded edges..... Maybe us a mirror with 400 paper..
As it's getting old, probably compression is probably down a bit. I don't use sealant on head gaskets. I scrape old gasket off with a snap off blade... even a wire wheel...
Get the right plug...
Tighten the head down, and a second time after a couple of hours use. If you don't have torque wrench, tighten it firm, before stripping it.
I'm putting one together tomorrow.........
good luck
speedy
